Elevation gradients provide an ideal setting to infer species' functional trait responses to predicted future climate change. In plants, leaf functional traits help assess their capacity to cope with varying resources. Variation in abiotic conditions over short vertical distances can influence plant phenology, particularly leafing and flowering durations, and leaf functional traits at both inter- and intra-specific levels. However, studies examining relationships between leaf functional traits and phenology duration along elevation gradients are limited. We tested the relationship between leaf size, leaf thickness, specific leaf area, and leafing durations in 10 Rhododendron species in the Sikkim Himalaya. All the investigated traits varied significantly across species, but intra-specific variation in functional traits was observed only among a few. Leaf size and thickness showed significant negative relationships with elevation and a comparative phylogenetic method exhibited a strong relationship between leaf traits and leafing duration. We observed higher leaf thickness and size in species with longer leafing durations and less overlap in leafing and flowering durations. In contrast, species with shorter leafing durations and relatively more overlap in their flowering and leafing durations showed lower leaf thickness and leaf size. Leaf traits such as leaf thickness and leaf size also exhibited a strong phylogenetic signal across 10 Rhododendron species. Overall, from our findings, we infer that along an elevation gradient, the magnitude of leaf trait responses to future increases in temperature may vary depending on species phenology durations and phylogeny.

海拔梯度为推断物种对预期的未来气候变化的功能性状响应提供了理想的环境。在植物中，叶片功能性状有助于评估其应对各种资源的能力。非生物条件在短垂直距离上的变化会影响植物物候，特别是叶片和开花时间，以及种间和种内水平的叶片功能性状。但是，研究沿着海拔梯度的叶片功能性状与物候持续时间之间的关系的研究是有限的。我们在10个杜鹃花中测试了叶大小，叶厚度，比叶面积和生叶持续时间之间的关系锡金喜马拉雅山中的物种。所有调查的性状在物种之间差异很大，但仅在少数物种中观察到功能性状的种内差异。叶的大小和厚度与海拔高度呈显着负相关，比较的系统发育方法显示叶性状与生叶持续时间之间有很强的关系。我们观察到，具有较长叶期的物种的叶片厚度和大小更高，而叶期和开花期的重叠较少。相反，具有较短生叶时间并且开花和生叶时间相对较多重叠的物种显示较低的叶片厚度和叶片尺寸。在10个杜鹃花上，叶片特征（例如叶片厚度和叶片大小）也表现出较强的系统发生信号种类。总体而言，从我们的发现中，我们推断出，沿着海拔梯度，叶片性状对未来温度升高的反应幅度可能会因物种物候持续时间和系统发育而异。